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United States Patent | 6,104,195 |
Yoshinaga ,   et al. | August 15, 2000 |
An apparatus for detecting a condition of burning in an internal combustion engine includes a pair of opposed electrodes provided in a combustion chamber of the engine, and an AC voltage applying device for applying an AC voltage between the opposed electrodes. A current detecting device is operative for detecting a current flowing between the opposed electrodes. A current generating means for generating a current-representing signal depending on the detected current, the current generating means having a differentiating circuit for differentiating the AC voltage into the capacitance-current representing signal. In another aspect of this invention, the apparatus further comprises calculating means for calculating ratios between a parameter represented by the burning-ion current representing signal and a parameter represented by a signal depending on the AC voltage applied between the opposed electrodes. A waveform processing device is operative for removing the capacitive current component from the current-representing signal to extract a burning ion current component, and for generating a burning-ion-current representing signal depending on the extracted burning ion current component. The capacitive current component occurs in correspondence with the AC voltage. One aspect of the invention utilizes calculating means for calculating a ratio between a parameter represented by the burning-ion-current representing signal and a parameter represented by a signal depending on the AC voltage applied between opposed electrodes. The burning ion current component corresponds to a burning ion current which flows between the opposed electrodes. A burning condition detecting device is operative for detecting a condition of burning in the combustion chamber of the engine on the basis of the burning-ion-current representing signal generated by the waveform processing device. The waveform processing device includes an integration processing device for integrating the current-representing signal to generate the burning-ion-current representing signal.
Inventors: | Yoshinaga; Tohru (Okazaki, JP); Kohama; Tokio (Nishio, JP); Yorita; Hiroshi (Kariya, JP); Satou; Yasuyuki (Aichi-ken, JP); Kano; Masao (Gamagoori, JP); Yamaura; Toshiaki (Anjo, JP) |
Assignee: | Denso Corporation (Kariya, JP); Nippon Soken Inc. (Nishio, JP) |
Appl. No.: | 832201 |
Filed: | April 8, 1997 |
May 10, 1995[JP] | 7-137377 | |
Mar 04, 1996[JP] | 8-75215 | |
Apr 08, 1996[JP] | 8-085044 |
Current U.S. Class: | 324/459; 73/23.31; 73/35.08; 73/116; 324/392 |
Intern'l Class: | F02P 017/12; G01N 027/62 |
Field of Search: | 123/425,481 73/35,116,23.31,35.08 324/399,459,391,392,393,464 |
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